With the fast development of services such as wideband, internet protocol (IPTV) and video data transmission, new requirement for transport network is brought forward. The transport network should not only provide wide bandwidth, but also have flexible dispatch capability and perfect operation administration and maintenance (OAM) function. The transport network in relative technologies mainly uses synchronous digital hierarchy (SDH) technology or wavelength division multiplexing (WDM) technology. Both of the two technologies have advantages and disadvantages.
SDH technology mainly processes electric layer signal, whose advantage lies in flexible dispatch capability, rich protection function and perfect OAM. However, the current maximal dispatch granule of SDH is virtual container VC4 with relatively small dispatch granule, which cannot satisfy the increasing service demands. The WDM technology mainly processes optical layer signal, and provides large bandwidth by multiplexing a plurality of wavelengths. However, there is physical limitation in the optical layer process, such as photo damage, wavelength conversion and so on, therefore it does not have flexible dispatch capability and rich protection function of the electric layer signal process. Hence, the WDM technology is generally used in point-to-point or ring network scene.
Aiming at the respective disadvantages of SDH and WDM, the International Telecommunications Union-Telecommunications standardization sector (ITU-T) provides new transport hierarchy frame-optical transport network (OTN). The OTN technology comprises optical layer and electric layer. Network survivability mechanism exists in either layer, and there is a corresponding management monitoring mechanism between the optical layer and the electric layer to solve the above described problems. Meanwhile, the OTN network provides strong OAM function, and can perform flexible dispatch to the services with different granules when relatively large bandwidth is provided.
Though the OTN technology solves the respective disadvantages of SDH and WDM technologies, it brings a new problem as well: the optoelectronic interlayer adapting problem. In an OTN apparatus, when establishing an optical channel (OCh) layer network connection, because of the limitation of the wavelength, to realize such functions as optic-electric-optic (O-E-O) wavelength conversion, and the regeneration of reamplifying, reshaping and retiming (3R), service signal need to pass through OCh→optical channel transport unit k (OTUk)→optical channel data unit k (ODUk)→OCh. But if the service signal passes through the optical and electric layers, the signal will need to pass through (OCh)→(OTUk)→ODUk, or ODUk→(OTUk)→OCh. Therefore, OCh/OTUk can be used as OTN interlayer processor.
The current technology of OTN device management describes the functions of wavelength conversion, 3R regeneration, conversion between optical layer service signal and electric layer service signal in different scenes, For instances, the wavelength converter functions as the wavelength conversion information in wavelength switch optical network (WSON) model; OCh and ODUk interlayer adapter functions as the multiple layer network/multiple region network (MRN/MLN) interlayer adapting information. The information is abstracted respectively and is not associated, so that the management and maintenance of information is complicated.